The present invention relates to a self-propelled apparatus for removing a thickness of asphalt paving from an asphalt roadway and for reprocessing the removed asphalt so as to permit the recycling thereof.
Deteriorating asphalt roadways have in the past been rehabilitated by a process wherein the top layer of the asphalt roadway is removed by a drum type milling machine which is advanced along the roadway. The removed asphalt is then trucked to a reprocessing plant where the removed asphalt is usually blended with new aggregate and hot liquid asphalt in a rotary heater, to form a new asphalt paving material. This new material is then trucked back to the roadway while hot and laid on the roadway by a conventional paver.
As an alternative to the above process, a process has recently been developed which involves the cold, in-place recycling of asphalt, and which substantially reduces the transportation and heat energy costs associated with the above described process. This cold process has heretofore been carried out by a complex apparatus composed of a train of three separate roadway units positioned in tandem. The first unit includes a drum milling cutter for removing the top layer of the asphalt surface. The second unit receives the removed material on an inlet conveyor and has a vibratory screen for separating the material by size, with the relative fine portion dropping onto a discharge conveyor and the oversize portion being directed into a crusher and returned by a conveyor back to the inlet conveyor for recirculation through the vibratory screen. The final unit receives the proper, i.e. fine, material on a weigh conveyor, and a controlled amount of liquid asphalt or asphalt emulsion is added based upon the weight of the material. The mixture then passes through a pugmill type mixer and is discharged onto the roadway. A conventional paver follows the train, and forms the discharged material into pavement.
As will be apparent, the above described apparatus for the cold, in-place recycling of asphalt is structurally complex and expensive. More particularly, the train of roadway units incorporates a large number of separate conveyors, which are expensive and require separate maintenance. Also, the train of roadway units is large and cumbersome, and it cannot back up.
It is accordingly an object of the present invention to provide an apparatus for performing the cold, in place recycling of asphalt pavement which substantially avoids the limitations and disadvantages of the presently employed apparatus as described above.
It is a more specific object of the present invention to provide an apparatus of the described type which comprises a single roadway unit, and which is designed to efficiently perform all of the functions of the presently employed train of roadway units.